U.S. Philips Corporation

Eric B Desbonnets

Joao N Ramalho

Luan Le

The present invention discloses an output stage for a charge pump, mainly formed by transistors, for example, MOS-type transistors. This output stage includes capacitive elements intended to compensate charge/discharge phenomena of parasitic capacitances intrinsic to the transistors. A charge pump including such a stage may thus produce a low-value nominal current and enables to completely integrate a phase-locked loop demodulator.

Output stage for a low-current charge pump and demodulator integrating

The invention relates to a system for reading magnetic information, comprising at least one read head H0 provided with two magnetoresistive rods (MR10, MR20) whose electrical resistivities (RMR10, RMR20) vary in mutually opposite senses when they are subjected to a same variation in magnetic field. According to the invention, the reading system comprises a detection module DET which comprises two resistors R of substantially the same resistance value, an amplifier A having one input and one output, and a comparator Cp having two inputs and one output. Each resistor R has a terminal connected to the output terminal (M10, M20) of one of the magnetoresistive rods, while the other terminals of the resistors are interconnected so as to form a common junction point NC. The voltage of the common junction point NC is amplified and compared with a reference voltage Vref by the comparator Cp. The output of the comparator Cp signals an accidental contact between the read head and a foreign body or asperity which may be present on the surface on which the information is stored.

System for reading magnetic information provided with a thermal asperity

A write amplifier comprising four current mirrors which are turned on two at a time by two switchable floating current sources between the input terminals of the current mirrors in order to produce a write current of alternating polarity through the write head. The parasitic capacitances across the write head and/or the parasitic capacitances of the write amplifier at the write terminals are compensated by means of feed-forward capacitors. The high impedance at the terminals of the write head enables the common-mode voltage across the write head to be fixed at any desired voltage value by means of a common-mode circuit.

Growing community of inventors

Caen, France

Eric B Desbonnets